Targeting messages to people at higher risk of cancer or with increased receptivity can enhance the efficiency and effectiveness of prevention and early detection efforts. Relatives of cancer patients near the time of diagnosis may be a receptive population due to a higher and more salient sense of their cancer risk. Public health and patient intervention strategies must be informed by understanding: 1) the complex process of adaptation to a relative's diagnosis; and 2) the variables that characterize subgroups of the population who may have specific needs. While these issues have been studied to some extent in relatives of breast cancer patients, important questions remain, including what factors influence and interact with perceived risk and emotional distress over time, the role of coping style and health behavior in the adaption process. It is known that risk perception and emotional distress vary widely among relatives, but the issues within distinct subgroups have not been characterized. The lack of information on these questions is partly due to the inherent limitations of cross- sectional designs. We propose a prospective, longitudinal investigation of the process of adaptation in a 520 first-degree female relatives of approximately 422 breast cancer "index" patients. We will pursue the following specific aims: Among relatives of cancer patients to: 1) Assess attitudes, knowledge, emotional distress, and coping, in relation to perceived risk; 2) Determine the natural history of screening participation and lifestyle behavior change over 12 months; 3) Engage in an extensive, theory-driven multi-factorial analysis to build models of how beliefs and behaviors are influenced over time. Among breast cancer patients, to: 1) Assess the patient's general level of distress, knowledge/perceptions about breast cancer, and advice given to relatives; and 2) Explore the relationship of the patient's report to their relatives' beliefs and adjustment. Patients will be contacted and interviewed in person within six weeks of their initial diagnosis. Their relatives will be interviewed by telephone at baseline (T0), and at 6-month (T1) and 12-month (T2) follow-ups. Constructs for the study have been selected from social cognitive formulations of social information processing and individual difference, specifically Miller's C-SHIP model. A majority of measures are standardized tools with respected validity and reliability. Data analysis will focus on the multi-variate modeling of the hypothesized paths, using a panel design over time, as well as on the characterization of patterns within clinically meaningful subgroups of the sample.